A user terminal using an Internet protocol (IP) may be a mobile node with multiple IP addresses such as two wireless broadband (WiBro) ports. Such a mobile node uses the first IP address to transmit and receive IP packet data and the second IP address as a reserve for the malfunctioning of the first IP address. In this case, the mobile node must use multiple IP addresses having an IP address system under the same medium and the same protocol.
Also, a user terminal may be a mobile node with multiple IP addresses such as cellular type MIPv6 address 1 and WiBro MIPv6 address 2. Such a mobile node uses the first address to transmit and receive IP packet data and the second address for a streaming service. In this case, the mobile node must use multiple IP addresses having the IP address system of the same protocol although the access medium is different.
As another example, a user terminal may be a mobile node with multiple IP address such as a cellular type MIPv6 address 1 and a session initiation protocol (SIP) type MIPv6 address 2. The mobile node uses two different IP addresses to receive a seamless service when the mobile node moves from a cellular type MIPv6 supported area to a SIP type MIPv6 supported area. In this case, the mobile node must have multiple IP addresses having an IP address system of different connection media and protocols.
In trains or airplanes, a mobile network may be provided. Such a mobile network may include various stationary nodes such as a temperature sensor or a pressure sensor and a portable phone having a wireless personal area network (WPAN). The mobile network can provide services by accessing the portable phone and the stationary nodes and connecting the portable phone to external networks. In such a case, the mobile network includes a mobile router to make a connection to an external network. Such a mobile router functions as a gateway connecting a mobile network to an external network. A plurality of nodes may exist in the mobile router, and have the same or different media and signal protocols for handoff. Also, the mobile network may include a plurality of mobile routers to access the external networks, and the mobile routers may use same or different access mediums and signal protocols for handoff.
A large-sized mobile station such as a passenger ship cruising around a long distanced area may include a plurality of mobile networks having sub networks for each floors of the passenger ship. Each of the mobile networks includes multiple mobile routers to make a connection to an external network, and the mobile routers may use the same or different signal protocols for handoff.
If the mobile nodes (MN) or the mobile routers (MR) are allowed to use multiple IP addresses or separate subnets as described above, the mobile nodes or mobile routers depend on the policy of a home agent where the MNs and the MRs are belonged to.
As a conventional technology, a mobility management method was introduced in U.S. Pat. No. 6,990,339 B2 issued to Turanyi et al. and entitled “Mobility Management for Mobile Hosts”. The introduced mobility management method can be used for a MIPv4 node and a MIPv6 node. In the mobility management method, a network address identifier (NAI) and a user name service (UNS) were introduced. The NAI is placed between a home agent (HA) and a foreign agent (FA) on a packet path between a correspondent node (CN) and a mobile node (MN) and prevents packet transmission delay and packet loss which may occur if the HA and the FA intervene whenever packet transmission is delayed or handoff occurs. The UNS has a function for mapping IP addresses (CoA) of places where a NM visits. In this method, whenever a MN moves to a FA, the MN transmits an IP address (CoA) obtained from a new FA to a home UNS, and the MN also transmits a message to a CN to inform that the MN moves to a new FA so that the CN obtains the new IP address (CoA) of the MN from the home UNS of the MN to transmit packets. Or, the MN can directly transmit an IP address (CoA) obtained from the new FA to the CN after encoding the obtained IP address (CoA). In this case, the CN receives a key value for decoding the encoded IP address from the home UNS of the MN and obtains the IP address of the MN. Then, the CN transmits packets to the obtained IP address of the MN.
The conventional management method has advantage that a registration procedure is not required and the HA or the FA is not included in a packet path. But, the conventional management method requires the CN and the UNS to have a capability of communicating, and the CN to have the home UNS of a MN if the CN wants to access the MN before the MN accesses the CN. That is, backward compatibility problem is arisen. Also, the MN is required to have a function to recognize and transmit related messages to the UNS or the CN. If the home UNS of the MN is located at long distance, a CN takes long time to obtain an IP address, thereby delaying packet transmission. Therefore, the usability thereof is limited into a mobile node, not into a mobile network.
Another conventional mobility management method was introduced in U.S. Pat. No. 7,065,062 B2 issued at Jun. 20, 2006 and entitled “Mobile Ip mobility management at dormant hand-over in CDMA IP-based cellular packet-data network”. This mobility management method can be used for Mobile IPv4 and Mobile IPv6. This conventional mobility management method is a plan to simplify a complex handoff procedure of a dormant mobile node in a CDMA-2000 mobile phone. It is difficult to perform high speed handoff required to registration when a mobile node not in a dormant state changes a FA, that is, when an active mobile node changes a FA.
Furthermore, a conventional mobility architecture, as another related technology, was introduced in U.S. Patent Publication No. 2005/0163078 A1 published at Jul. 28, 2005, and entitled “Mobility architecture using pre-authentication, pre-configuration and/or virtual soft-handoff”. In the introduced mobility architecture, a pre-authentication for L2 layer of IEEE 802.11 is extended. That is, in order to perform handoff between local area networks (LAN) having different subnets, a L3 layer is pre-configured and pre-authenticated by sensing a beacon signal of an adjacent access point (AP) is sensed before L2 handoff occurs. Therefore, when an IP handoff occurs according to the movement of a mobile node, resources for necessary IP address are previously allocated in the mobility architecture. The mobile architecture has advantages of safe and rapid L3 handoff in networks such as LAN, Home RF, Wi-Fi, CDMA, TDMA, GSM, and CDMA2000. When a mobile node moves and detects a L2 layer beacon signal of an adjacent area, the mobile node performs the pre-configuration and the pre-authentication of a L3 layer, that is, an IP address before L2 handoff occurs. When the L2 handoff occurs, the MN instantly changes to the IP address of a current subnet.
The conventional mobility architecture requires a mobile node to have a function for performing a pre-configuration and a pre-authentication for a L2 handoff before the L2 handoff occurs. Therefore, a terminal used in a typical public mobile communication network cannot be used. Also, a MN is required to determine whether a received beacon signal is a beacon signal from an AP in a new subnet or not whenever a mobile node receives beacon signals from a new AP in the same subnet area. That is, the MN is required to process even until the L3 layer to determine whether the mobile node moves to different subnets whenever the mobile node receives a beacon signal of a new AP.
Meanwhile, a handoff process method using a SIP protocol as an IP handoff method was introduced in rfc2543 of IETF. The handoff process method using a SIP protocol is similar to the present invention in a view that a data packet path is separated from a signaling packet path. However, the handoff process method using the SIP protocol requires a SIP redirect server to register whenever IP address changes. Therefore, a handoff time delay becomes lengthened when a mobile node moves far away from a home network. Also, it is difficult to sustain the continuity of TCP session due to the IP address change while a mobile node is moving. In order to sustain the continuity of TCP session, an Internet technologies supporting universal mobile operation (ITSUMO) project was introduced. That is, when a MN changes an IP address while sustaining the TCP session, the handoff is processed using information formed of the original IP address of the MN, the current IP address of the MN, the original IP address of a correspondent host using a current TCP session. However, this method has difficulty to embody a SIPeye agent in a related correspondent host and all MNs. When a mobile IPv6 is used, a hierarchical MIPv6 registration method was introduced. In this method, it requires to be aware of an IP address of an agent of a network where a MN visits. That is, the hierarchical MIPv6 registration method also has the regional registration problem.
A high speed handoff method using a satellite was introduced. The high speed handoff method was developed for voice communication, not for IP packet. Also, the high speed handoff method has a problem of high cost because it requires the satellite. In case of using a satellite such as a geostationary satellite, it has a problem of serious time delay between a node in an earth and a satellite, and a HOL problem because paths for data packet and the handoff signal packet are identical.
In order to overcome problems of conventional handoff technologies, a mobile router is required to have a plurality of IP addresses or support heterogeneous address systems. Also, it requires a method of supporting a mobile network to use a plurality of mobile routers for connecting external network.